Apparatus for continuously centering a moving strip



June 25, 1957 E. T. Lowe 2,797,083

APPARATUS FOR CONTINUOUSLY CENTERING A MOVING STRIP Filed Sept. 17, 1953 2 Sheets-Sheet l June 25, 1957 E. T. LORHG APPARATUS FOR CONTINUOUSLY CENTERING A MOVING STRIP V Filed Sept. 17, 1953 2 Sheets-Sheet 2 APPARATUS FQR CONTIINUOUSLY CENTERING A MOVING STRIP Edwin T. Lorig, Pittsburgh, Pa, assignor to United States Steel Corporation, a corporation of New Jersey Application September 17, 1953, Serial No. 380,647

9 Claims. (CE. 271-26) This invention relates to apparatus for continuously centering a moving strip and is particularly adapted for centering steel strip being processed at high speed. Since most strip, and steel strip in particular, is not uniform as to transverse and longitudinal shape the problem of tracking the strip properly has plagued industry for many years. The different types of strip shape or contour variances and theiretfect on tracking will not be described here in detail since they are well known to the operator. Camber, edge wave and buckle commonly appear in the strip in various combinations. Change in temperature of the strip passing through the processing line increases the problem. Such processing lines generally have mechanical loopers or looping pits for free hanging loops to take up and provide slack at each end of the line. Free hanging loops of comparatively great depth invariably cause trouble at high operating speeds because the strip in the loop twists and turns first one way and then the other with an action that at times becomes extremely violent. Increased tension on the strip passing through the line has been resorted to in order to improve tracking, but the tension cannot be increased above their present limits without causing damage to the equipment and strip. There has been a tendency to increase strip speed and length of lines in order to effect economies in equipment and operating costs, but this increased speed and .longer lines increase lateral weaving and lateral divergence and usually requires additional looping pits with exit guides. Thus it is seen that the problem of proper tracking is a very important and difiicult one. The selfcentering rolls disclosed in my Patents Nos. 2,593,157, 2,593,158 and 2,592,581 all dated April 15, 1952, have accomplished much in improving the tracking of strip through processing lines. Further advances have been made by the use of the apparatus disclosed in my copending application, Serial No. 284,379, filed April 25, 1952, now Patent No. 2,706,625, dated April 19, 1955. However, in some instances, when handling strip of very poor transverse and longitudinal shape at high speeds the centering ability of the equipment described above is not great enough to overcome the lateral weaving.

It is therefore an object of my invention to provide a roll assembly having very strong centering ability when strip or other elongated objects passes thereover.

Another object is to provide a strip processing line for handling strip at high speeds with a minimum of lateral weaving and divergence.

These and other objects will be more apparent after referring to the following specification and attached drawings in which:

Figure 1 is a schematic view of the roll assembly of my invention;

Figure 2 is a view taken on the line II--II of Figure 1;

Figure 3 is a view taken on the line III--III of Figure 1;

Figure 4 is a schematic view of a tight strip processing line; and

States atent 2,797,088 Patented June 25, 1957 Figure 5 is a schematic view of a strip processing line having a looper pit therein.

Referring more particularly to Figures 1 to 3 of the drawings the reference numeral 2 indicates a narrow bodied roll around which passes strip S. From the roll 2 the strip S passes around a self-centering roll 4 and then around a second narrow bodied roll 6. As shown in Figure 2 the narrow bodied rolls 2 and 6 are identical and have a cylindrical strip supporting surface 8 of considerably less width than the strip S. The rolls 2 and 6 are supported for rotation in axially aligned spaced bearings 10. In some instances an extension 12 is provided on the roll shaft 14 to provide a driving connection to rotate the roll. In other instances the rolls 2 and 6 will be idler rolls rotated by strip contact only. For very severe operating conditions the narrow bodied rolls 2 and 6, instead of being solid rolls, will be self-centering rolls of the type disclosed in my above mentioned patents. For example, the rolls may be hollow rolls split on their transverse centers 16 as shown in my Patent No. 2,593,158. Roll 4 is a self-centering roll of the type disclosed in my above mentioned patents. The particular roll shown in Figure 3 is preferred but other constructions may be used. The roll of Figure 3 consists of a straight shaft 18 having two substantially cylindrical roll sections 20 supported thereon and mounted for rotation with the shaft by means of collars 22'fastened to the shaft, each collar having a pin 24 thereon extending into a hole 26 in the end of the adjacent roll section. The shaft 18 is mounted for rotation on axially aligned bearings 27 and may be provided with a drive extension 28.

All the self-centering rolls discussed above have roll sections on opposite sides of the transverse center of the roll which roll sections rotate at the same angular velocity and which are so constructed that an axial force directed inwardly toward the transverse center of the roll is provided at the points of contact with the strip, thus tending to keep the strip on center regardless of outside forces. The spacing of the rolls 2, 4 and 6 may vary but it is desirable to have the roll 2 on the approach side of roll 4 spaced a' considerable distance from the roll 4 and the roll 6 fairly close to the roll 4. When the roll assembly is used in reversible processing lines the roll 4 will preferably be equidistant from the rolls 2 and 6. The strip must pass around a considerable arc of each of the rolls and preferably should pass around at least of the roll if possible. However, the strip need not go around the rolls 2 and 6 in the direction indicated. Instead the strip could approach roll 2 and leave roll 6 from the bottom and be wrapped around these rolls in a counterclockwise direction instead of clockwise as shown. The roll assembly described acts to center and align the strip on the roll 4 regardless of normal shape variances. The centering and aligning effects on the strip are reflected a considerable distance in both directions from the roll 4. It should be observed that the solid narrow bodied rolls have no centering ability in themselves but do have the ability to slightly distort and change the planes in the moving strip in the proper direction to combine with the centering effect of the self centering roll to maintain suitable strip edge alignment. The particular roll shown in Figure 3 increases the tension slightly on one edge of the strip and decreases it on the other as slight lateral movement of the strip occurs, thus causing the succeeding roll on the delivery side to tilt the strip edges automatically in the proper direction to secure recentering and alignment of the strip.

Figure 4 shows a typical strip processing line which utilizes the roll assembly of my invention and which does not require edge guides. This line may be termed a tight line since the strip is under tension throughout the line and no looper pits are utilized. The strip S passes from an unwinding reel 30 around a narrow bodied rubber covered self-centering roll 32 preferably of the type shown in my Patent No. 2,592,581. From the roll 32 the stripv passes around rolls 34 and' 36 to the processing equipment 38. The roll 34 is a self-centering roll preferably of the type shown in Figure 3 and the roll 36 is a narrow bodied solid roll. It will be seen that the rolls 32, 34 and 36 constitute a roll assembly as shown in Figure 1. In the processing equipment the strip S passes around rolls 40 which are preferably narrow bodied rolls. However, the upper rolls may be self-centering rolls in which case they form with the narrow bodied rolls additional centering roll assemblies. From the processing equipment 38 the strip passes around a narrow bodied roll 42 and hence to and around a selfcentering roll 44' preferably of the type shown in Figure 3'. The strip S then passes to the tension bridle 4.6 consisting of rolls 48, 50, 52, 54 and 56. The rolls 48 and 52 are narrow bodied self-centering rolls of the type shown in my Patent No. 2,592,581 and the rolls 50 and 54 are full width rolls of the type shown in my Patent No. 2,592,581. It is preferred to have the rolls 48, 50, 52 and 54 constructed with slits as shown in my copending application, Serial No. 380,646 filed'September 17, 1953, now- Patent No. 2,772,879, dated December 4, 1956, instead of with the comparatively wide grooves shown in Patent No. 2,592,581. The roll 56 is a plain cylindrical roll and may be omitted if desired. I have found that rolls of the type shown in my Patent No. 2,592,581, operate very satisfactorily in strip processing lines when used as bridle or pinch rolls, especially when modified asdescribed above. The rolls 42, 44 and 48 constitute a roll assembly of the type shown in Figure 1. From the, roll 54 the strip passes around a self-centering roll 58 which may be either a full bodied or narrow bodied roll similar to rolls 48 or 50. The strip S then passes to the winding reel 60. In strip processing lines it is preferred that each roll have a strip wrap of at least 90 and that opposite sides of the strip contact successive rolls. All of the rolls are preferably either narrow bodied cylindrical solid rolls or self-centering rolls. The strip S is preferably under low tension between the unwinding reel and the bridle rolls, under medium tension in the bridle rolls and under tension between the tension bridle and the winding reel so as to produce a tightly wound coil. The line shown in Figure 4 may be provided wtih mechanical loopers or free hanging loops in looper pits arranged in the usual manner.

Figure shows an arrangement of a looper pit in a processing line which permits use of alooper pit without the disadvantages mentioned above. The strip S passes from an uncoiler 62 around a self-centering roll 64, preferably of the type shown in my Patent No. 2,592,581, through theprocessing equipment 66 and then over and around a self-centering roll 68 preferably of the type shown in my Patent No. 2,593,157, then down around a narrow bodied roll 70, up and around a self-centering roll 72, preferably of the same type as roll 68, and then down around a narrow bodied rubber covered centering roll 74 of the type shown in my Patent No. 2,592,581. The rolls 7t), 72 and 74 constitute a centering roll assembly. A full bodied rubber covered centering roll 76 is arranged above roll 74 in pinch roll arrangement therewith and the strip S passes therearound. The strip S then forms a free hanging loop 78 having the roll 76 as one support and a self-centering roll 80 as the other support. From the roll 80 the strip passes down around narrow bodied roll 82 and up around self-centering roll 84 and then down and around narrow bodied rubber covered centering roll 86. The rolls 80 and 84 are preferably of the type shown in my Patent No. 2,593,157. The rolls 82, 84 and 86 form a centering roll assembly. The roll 86 together with rolls 88, 90 and 92 form a tension bridle. Therolls 88 and 92 are full bodied rubber covered centering rolls and the roll 90 is a narrow bodied rubber covered centering roll having slits therein. The strip S passes from the roll 92 around a roll 94 to a winding reel 96. The roll 94 may be either a rubber covered centering roll or a narrow bodied roll. The distance between rolls 76 and 80 should be sufiiciently long for the catenary loop 78 to provide sufiicient strip tension and flatness at the bottom to prevent the twisting and tangling action referred to above. It will be understood that additional looper pits may be provided in the line if necessary.

While several embodiments of my invention have been shown and described it will be understood that other adaptations and modifications may be made without departing from the scope of the following claims.

I claim:

1. A roll assembly for automatically centering a moving elongated object comprising a pair of spaced apart narrow bodied rolls arranged with their axes substantially parallel, each of said rolls having a substantially cylindrical object supporting surface of less width than the width of the object, and a self-centering roll mounted between said narrow bodied rolls substantially parallel thereto, said self-centering roll having two roll sectiQns one on each side of the transverse center of the roll and means forrotating the roll sections at the same angular velocity, said roll sections being constructed so as to provide axial forces directed inwardly toward the transverse center of the roll at the points of contact with the object, the object passing around a substantial arc of one of said narrow bodied rolls, then around a substantial arc of the self-centering roll and then around a substantial arcof the other of said narrow bodied rolls.

2. A roll assembly according to claim 1 in which said self-centering roll comprises a shaft, and a pair of substantially cylindrical roll sections supported on said shaft for rotation therewith, the adjacent ends of said roll sections being tiltable toward said shaft so as to form a concave object supporting urface.

3. A strip processing line comprising a plurality of narrow bodied rolls around a substantial arc of which the strip passes, and a pair of spaced apart roll assemblies one on each side of the plurality of narrowbodied rolls, each of said roll assemblies including a pair'of spaced apart narrow bodied rolls arranged with their aXes substantially parallel, each of said rolls having a substantially cylindrical strip supporting surface of less width than the width of the strip, and a selfcentering roll mounted between said narrow bodied rolls substantially parallel thereto, said self-centering roll having two roll sections one on each side of the transverse center of the roll and means for rotating the roll sections at the same angular velocity, said roll sections being constructed sov as to provide axial forces directed inwardly toward the transverse center of the roll at the points of contact with the strip, the strip passing around a substantial are of one of said narrow bodied rolls, then around a substantial arc of the self-centering roll and then around a substantial arc of the other of said narrow bodied rolls.

4. A strip processing line according to claim 3 in which said self-centering roll comprises a shaft, and a pair of substantially cylindrical roll sections supported on said shaft for rotation therewith, the adjacent ends of said roll sections being tiltable toward said shaft so as to form a concave strip supporting surface.

7 5.-A strip processing line comprising a plurality of narrow bodied rolls around a substantial arc of which the strip passes, a tension bridle adjacent the exit end of said processing line including a pair of automatic centering pinch rolls, and a pair of spaced apart roll assemblies one between the plurality of narrow-bodied rolls and the'tension bridle and the other before the plurality of narrow-bodied rolls, each of said roll assemblies including a pair of spaced apart narrow bodied rolls arranged with their axes substantially parallel, each of the last named rolls having a substantially cylindrical strip supporting surface of less width than the width of the strip, and a self-centering roll mounted between said narrow bodied rolls substantially parallel thereto, each of said self-centering rolls having two roll sections one on each side of the transverse center of the roll and means for rotating the roll sections at the same angular velocity, said roll sections being constructed so as to provide axial forces directed inwardly toward the transverse center of the roll at the points of contact with the strip, the strip passing around a substantial arc of one of said narrow bodied rolls, then around a substantial arc of the self-centering roll and then around a substantial arc of the other of said narrow bodied rolls.

6. A strip processing line according to claim in which said self-centering roll comprises a shaft, and a pair of substantially cylindrical roll sections supported on said shaft for rotation therewith, the adjacent ends of said roll sections being tiltable toward said shaft so as to form a concave strip supporting surface.

7. In a strip processing line having a free hanging loop of strip, a pair of spaced apart roll assemblies one on each side of said free hanging loop, each of said roll assemblies comprising a pair of spaced apart narrow bodied rolls arranged with their axes substantially parallel, each of said rolls having a substantially cylindrical strip supporting surface of less width than the width of the strip, and a self-centering roll mounted between said narrow bodied rolls substantially parallel thereto, each of said self-centering rolls having two roll section one on each side of the transverse center of the roll and means for rotating the roll sections at the same angular velocity, said roll sections being constructed so as to provide axial forces directed inwardly toward the transverse center of the roll at the points of contact with the strip,

the self-centering roll and then around a substantial arc of the other of said narrow bodied rolls.

8. In a strip processing line according to claim 7, said self-centering roll comprising a shaft, and a pair of substantially cylindrical roll sections supported on said shaft for rotation therewith, the adjacent ends of said roll sections being tiltable toward said shaft so as to form a concave strip supporting surface.

9. A roll assembly for automatically centering a moving elongated object comprising a self-centering roll around which the object passes, said selfcentering roll having two roll sections one on each side of the transverse center of the roll and means for rotating the roll sections at the same angular velocity, said roll sections being constructed so as to provide axial forces directed inwardly toward the transverse center of the roll at the points of contact with the object, and a second roll arranged in tandem with said self-centering roll on the exit side thereof and around an arc of which the object passes, said second roll having a cylindrical object supporting surface of considerably less width than the width of the object.

References Cited in the file of this patent UNITED STATES PATENTS 169,573 Parr Nov. 2, 1875 2,590,699 Heyer Mar. 25, 1952 2,592,581 Lorig Apr. 15, 1952 2,593,158 Lorig Apr. 15, 1952 2,622,875 Lorig Dec. 23, 1952 OTHER REFERENCES United States Steel Publication, adv., 19816-53, Lorig-Aligner Self-Centering Rolls. (Copy received in Division 17, June 9, 1953.) 

